The structure and functional activity of the centrosome was analyzed in hepatocytes of 5-day old mice, as well as the lengths of Golgi complex cisternae. In the early postnatal development of mice, the liver was represented by two types of hepatocytes: in the first type hepatocytes, the centrosome was active as a microtubule organizing center, while in the second type hepatocytes, it was inactive. It was proposed that during ontogenesis the centrosome is inactivated as a microtubule organizing center and activated as an organizing center of intermediate filaments characteristic for differentiated hepatocytes of adult liver. Morphometry of the Golgi complex has shown that Golgi cisternae in the cell center area of early postnatal hepatocytes were longer than in the adult hepatocytes and comparable to those in G 1-phase hepatocytes of regenerating liver. The possibility of relations between the differences in the Golgi complex morphology and ontogenetic changes in the functional activity of centrosomes is discussed.